Because the advantages of energy conservation and environment protection, portability, the LCD (Liquid Crystal Display) has been widely applied and promoted. As being an advertising board for the exhibition, several LCDs are often in mosaic exhibit for playing the same pictures or videos. However, with the chroma difference or the LCD manufacture process difference of the backlight module in the LCD, the same color may have the different display results in the different LCDs, and influences the exhibition result.